The present invention relates to construction materials to protect the exterior of houses and other structures. More particularly, the present invention relates to fiber-cement soffits for installation under the eaves of houses, commercial buildings and other structures.
A significant portion of the construction industry builds residential and commercial structures. Contractors generally build structures in-situ at specific sites, and xe2x80x9cmanufactured buildersxe2x80x9d generally build sections of structures in a factory for assembly at a particular site. In either application, the structures are generally framed, roofed and then covered with exterior siding materials. One particularly advantageous and popular type of siding is fiber-cement siding. Fiber-cement siding products are typically made from a composition having cement, cellulosic materials and a binder. The fiber-cement composition is pressed, cured and then cut into panels, shakes and planks to form finished siding products that are ready to be installed on a structure. Fiber-cement siding products are insect resistant, fire resistant, and wear resistant. Fiber-cement siding products can also be painted like wood, but they are not made from a valuable natural resource. Therefore, many contractors and manufactured builders are switching to fiber-cement siding products from wood, composites, aluminum, plastic and bricks.
Several buildings also have soffits installed under the eaves where the roof overhangs the exterior walls. Soffits are conventionally made from wood, metal (aluminum) or plastics. Soffits typically have large holes that are covered with a large mesh screen or thin slots to provide ventilation and to prevent insects or birds from nesting within the structure. The large holes, for example, are generally 1.5-3.0 inch diameter circles or 2xc3x9712 inch rectangles that are cut with a jig saw or a cylindrical saw. Wood and wood composite soffits, however, have several drawbacks because they are subject to insect infestation, warping, rotting and fire. Aluminum and plastic soffits also have drawbacks because they are difficult to paint, and thus the color of the soffits may be substantially different than the color of the paint on the exterior siding. Therefore, because fiber-cement building products do not suffer from the same drawbacks as wood, plastic or aluminum building products, many contractors and manufactured builders would like to install soffits made from fiber-cement.
Manufacturing fiber-cement products, however, can be difficult because fiber-cement building products are more difficult to process than wood, plastics or aluminum. For example, cutting fiber-cement products with circular saws (e.g., a rotating abrasive disk) produces a significant amount of dust that makes the working environment unpleasant and difficult to clean. Fiber-cement building products are also relatively brittle and can easily crack during processing. Moreover, fiber-cement building products are much more abrasive than wood, plastics or aluminum, and thus they wear through cutting tools very quickly. Fiber-cement soffits are particularly difficult to manufacture because it is difficult and time-consuming to form apertures in fiber-cement panels that allow air to flow through the soffits. Thus, fiber-cement soffits are not yet widely used in the marketplace.
One particularly promising fiber-cement soffit is a 12-foot fiber-cement panel having a plurality of xe2x85x9 inch diameter apertures in a uniform, symmetrical pattern. Manufacturers of fiber-cement building products, such as James Hardy Building Products of Fontana, Calif., have experimented with manufacturing such fiber-cement soffits by drilling the apertures. Drilling the fiber-cement panel, however, is not generally feasible in large scale production because it is too time-consuming and the abrasive fiber-cement quickly wears down the drill bits. Drilling the fiber-cement panel also produces a fine dust that is unpleasant and difficult to clean. Therefore, drilling the apertures in the fiber-cement panel is not a viable manufacturing process.
To overcome the problems of drilling fiber-cement panels, manufacturers of fiber-cement building products have also experimented with punching individual holes through a fiber-cement panel using a sheet metal punch. Typical sheet metal punches have a very small clearance between the punch and the die. Punching apertures through the fiber-cement panel with a sheet metal punch is also not feasible because the sheet punch metal often sticks to the fiber-cement panel. The sheet metal punch may thus delaminate portions of the panel as it withdraws from the aperture. Punching apertures through the fiber-cement panel with a sheet metal punch may also produce a mushroom-shaped plug such that each aperture has a small opening on the front side but a much larger opening on the back side. In preliminary tests using a sheet metal punch to form apertures in a fiber-cement panel, the sheet metal punch ripped out so much material from the backside of the panel that a typical 12-foot soffit may not have sufficient structural integrity to be hung under the eaves of a structure.
The present invention is directed toward methods and apparatuses for producing fiber-cement soffit building products. In one embodiment of the invention, an apparatus for producing fiber-cement soffits includes a punch assembly, a support assembly facing at least a portion of the punch assembly, and an actuator operatively coupled to at least one of the punch assembly or the support assembly. The punch assembly can include a punch plate and a plurality of punches coupled to the punch plate. Each punch can have a length and a first cross-sectional dimension generally normal to the length. The support assembly can have a support plate, and at least a portion of the support plate is juxtaposed to at least a portion of the punch plate. The support plate can include a plurality of holes arranged in a pattern so that each hole in the portion of the support plate juxtaposed to the punch plate is aligned with a corresponding punch on the punch plate. Each hole can have a second cross-sectional dimension greater than the first cross-sectional dimension of the punches to define a radial punch/hole clearance between each punch and each hole. The radial punch/hole clearance, for example, is generally greater than that of metal punch presses to allow the punches to be removed from a fiber-cement panel without delaminating portions of the panel.
The actuator can be coupled to the punch plate to move the punches between a first position and a second position. In the first position, the punches are spaced apart from the support plate to allow a fiber-cement panel to pass between the punches and the support plate. In the second position, the punches penetrate into the fiber-cement panel to form a plurality of apertures in the fiber-cement panel. The apertures generally have a first opening on a front side of the panel facing the punches and a second opening on the backside of the panel facing the support plate. The first openings can have shapes corresponding to the first cross-sectional dimension of the punches, and the second openings are slightly larger than the first openings. The apertures are thus frustoconical with only a slight change in diameter from the top to the bottom.
The punch and support assemblies can have several different configurations. In one particular embodiment, the punch plate is a first flat plate and the support plate is a second flat plate. Other embodiments of the punch plate and support plate include first and second cylindrical members, or devices having other shapes that can be pressed together. The punches coupled to the punch plate and the holes in the support plate can also have several configurations. In one particular embodiment, the punches have a concave contact face and a first diameter defining the first cross-sectional dimension. The first diameter, for example, can be approximately 0.11-0.25 inch. The holes in the support plate of this embodiment have a second diameter defining the second cross-sectional dimension. The second diameter can be approximately 0.18-0.39 inches. The radial punch/hole clearance between the punches and the holes in these particular embodiments can accordingly be approximately 0.032-0.070 inch. The radial punch/hole clearance can also be a function of the thickness of the fiber-cement panel or the size of the punch. For example, the radial punch/hole clearance between the punches and the holes can be approximately 4%-40% of the thickness of the fiber-cement panel or approximately 4%-30% of the diameter of the holes.
In one particular embodiment, the punch assembly includes a plurality of punches having a concave contact face, a first diameter of approximately 0.115-0.135 inch, and a biasing element surrounding each punch. The support plate of this particular embodiment can have holes with a second diameter of approximately 0.150-0.250 inch.
In the operation of this particular embodiment, the actuator drives the punch assembly toward the support plate until the punches penetrate through only a portion of the fiber-cement panel. The punches accordingly do not pass completely through the panel in this embodiment. Although the punches penetrate the fiber-cement panel only to an intermediate depth, the punches remove a frustoconical shaped plug from the panel to produce apertures through the full thickness of the fiber-cement panel. The biasing elements also press against the panel to prevent the panel from sticking to the punches as the punches withdraw from the fiber-cement panel. In this particular embodiment, the radial punch/hole clearance and the biasing elements prevent the punches from sticking to the fiber-cement panel to avoid or prevent delamination of the fiber-cement at the apertures.